Electronic logic elements in a variety of forms have been devised, known, and used for a considerable length of time. While such electronic logic elements are widely used, they nonetheless have a number of inherent disadvantages. One of the prime disadvantages of electronic optical elements is that, as with all electron devices, they are subject to cross-talk, intermodulation interference, and all the other common types of electromagnetic interference phenomena.
Moreover, as with all electronic devices, electronically operative logic elements produce an electromagnetic field in the course of their operation and therefore their actuation is not entirely secure in a military sense because there operative actuation can be detected by interception of the electromagnetic fields thus created.
Perhaps one of the most important disadvantages of electronic logic elements is the fact that each logic function must be performed separately and sequentially; that is to say, that electronic logic elements, as known in the present state of the art, perform but one separate logic function and the requirement to perform a number of different logic functions cannot be realized in a single logic element but only in a number of separate, discrete logic elements each of which is specifically designed and configured to perform its own distinctly different logic function. This, of course, implies a time requirement because of the fact that sequential logic functions may have to be performed in order to arrive at a desired result.
Accordingly, it is highly desirable that a generalized combined logic element be provided, obviating the separate sequential logic functions as must be performed with electronic logic elements. Additionally, it is also desirable that the disadvantages of cross-talk, intermodulation, electromagnetic interference effects, etc., be obviated and that a militarily secure means be provided for performing logic functions.
Optical gating in the operation of an optical OR gate has been reported by A. M. Glass and T. J. Negran in Applied Physics Letters, Vol. 24, No. 2, Jan. 15, 1974, at pages 81 and 82. The optical OR gate described in that publication employs photovoltaic phenomena to perform optical logic in pyroelectric waveguides. The waveguide material is single crystal lithium tantalate and, while reasonably satisfactory results have apparently been obtained experimentally, only separate, discretely operative OR and AND gates have been reported. It is apparent therefore that this prior art technique is not adaptable to provide a generalized logic element which will perform multiple logic functions within the same device configuration. Accordingly, the Glass and Negran technique is subject to the same limitation as electronic logic elements which require separate logic elements to perform separate logic functions.